1. Field of the Invention
This invention relates to the monitoring of concentrations of volatile organic compounds (hereinafter, VOCs) present in trace amounts (ppb) in waste gases, inclusive of combustion exhaust gases and incinerator effluents.
2. The Prior Art
The U.S. Environmental Protection Agency's (EPA) current regulatory approach for combustion and incineration sources emphasizes the real-time monitoring of trace process emissions including particulate, metals, and volatile, semivolatile, and nonvolatile organic compounds. Continuous emission monitors (CEMs) are needed to indicate emissions compliance, evaluate combustion process performance, and optimize process operation on a more timely, continuous basis. Unfortunately, the CEM technologies to support this approach have not been thoroughly developed and/or demonstrated. The ability to measure volatile organic compounds (VOCs) on a near-real-time basis is also valuable to research examining the formation and control of volatile organic products of incomplete combustion (PICs) from thermal treatment processes. The ability to measure VOCs on a near-real-time basis is also valuable to such important research which should be conducted in as short a time frame as possible.
A need also exists for a near-real-time indicator of combustion/incineration performance as a monitor of surrogate VOCs that may be indicators of dioxin emissions, considered to be the most toxic pollutant produced from combustion sources and as an inexpensive tool to screen combustion sources for hazardous air pollutants (HAPs).
Fourier Transform Infrared (FTIR) spectroscopy, is capable of making such measurements, but not with the sensitivity needed to measure typical PIC levels found in real-world systems.
Gas Chromatography (GC) is a mature technology that can be used to separate and identify trace compounds. However, a standard GC was found to have insufficient sensitivity with which to measure the PICs, which are present down to the 1 part per billion (ppb)concentration.